Figure 10.

Low-dose cytarabine decreases division and promotes differentiation of O-2A/OPCs.
Cells grown at clonal density were exposed 1 day after plating to low-dose cytarabine
(0.01 μM for 24 h), a dosage that killed less than 5% of O-2A/OPCs in mass culture
(Figure 9). The number of undifferentiated O-2A/OPCs and differentiated cells (oligodendrocytes)
was determined in each individual clone from a total of 100 clones in each condition
by morphological examination and by immunostaining with A2B5 and anti-GalC antibodies
(to label O-2A/OPCs and oligodendrocytes, respectively), as in Figure 4. (a) Composition of progenitors and oligodendrocytes in a representative experiment of
control cultures analyzed 6 days after plating optic nerve-derived O-2A/OPCs cells
at clonal density. (b) In parallel cytarabine (Ara-C)-treated cultures analyzed 6 days after plating at clonal
density (5 days after the start of cytarabine exposure), there was a marked increase
in the representation of small clones consisting wholly of oligodendrocytes, a reduction
in the representation of large clones, and a general shift of clone size towards smaller
values. Experiments were performed in triplicate in at least two independent experiments.